New Models Predict Greener Arctic in Coming Decades

Rising temperatures will lead to a massive “greening” of the Arctic by mid-century as a result of striking increases in plant cover, according to new research led by the American Museum of Natural History. In a paper published on March 31 in Nature Climate Change, scientists reveal new models projecting that wooded areas in the Arctic could increase by as much as 50 percent over the next few decades. This greening could also have a multiplier effect on warming at a rate greater than previously expected.

Arctic "greening" to come? Observed distribution (left) and predicted distribution of vegetation under a climate-warming scenario for the 2050s (right). Data used to generate the observed image are from the Circumpolar Arctic Vegetation Map (2003).

“Such widespread redistribution of Arctic vegetation would have impacts that reverberate through the global ecosystem,” said Richard Pearson, lead author on the paper and a research scientist at the American Museum of Natural History’s Center for Biodiversity and Conservation.

Plant growth in Arctic ecosystems has increased over the past few decades, a trend that coincides with increases in temperatures, which are rising at about twice the global rate. The research team—which includes scientists from the Museum, AT&T Labs-Research, Woods Hole Research Center, Colgate University, Cornell University, and the University of York—used climate scenarios for the 2050s to explore how this trend is likely to continue in the future.

The scientists developed models that statistically predict the types of plants that could grow under certain temperatures and precipitation. Although it comes with some uncertainty, this type of modeling is a robust way to study the Arctic because the harsh climate limits the range of plants that can grow, making this system simpler to model compared to other regions such as the tropics.

A scene in southern Greenland, as seen in 2008. How will Arctic vegetation be redistributed in the future? New research investigates.

John Sonntag/Wallops Flight Facility

The models reveal the potential for massive redistribution of vegetation across the Arctic under future climate, with about half of all vegetation switching to a different class and a massive increase in tree cover. What might this look like? In Siberia, for instance, trees could grow hundreds of miles north of the present tree line.

In addition, the researchers investigated the multiple climate change feedbacks that greening would produce. They found that a phenomenon called the albedo effect, based on the reflectivity of the Earth’s surface, would have the greatest impact on the Arctic’s climate. When the sun hits snow, most of the radiation is reflected back to space. But when it hits an area that’s “dark,” or covered in trees or shrubs, more sunlight is absorbed in the area and temperature increases. This has a positive feedback to climate warming: the more vegetation there is, the more warming will occur.

The new research shows that vegetation distribution shifts are likely to cause greater warming than has previously been predicted.